| LIU Shao-hui,WANG Jiao,WANG Fei-fei,WANG Yuan.Dielectric Energy Storage Performance of Alumina Coated SrTiO3 Nanofiber/Polyvinylidene Fluoride Composites[J],52(8):346-354 |
| Dielectric Energy Storage Performance of Alumina Coated SrTiO3 Nanofiber/Polyvinylidene Fluoride Composites |
| Received:July 06, 2022 Revised:November 22, 2022 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2023.08.029 |
| KeyWord:strontium titanate energy storage property nanofiber core shell structure interface modification dielectric property |
| Author | Institution |
| LIU Shao-hui |
Henan Key Laboratory of Electronic Ceramic Materials and Application,Henan International Joint Laboratory of Rare Earth Composite, Henan University of Engineering, Zhengzhou , China |
| WANG Jiao |
Henan Key Laboratory of Electronic Ceramic Materials and Application,Henan International Joint Laboratory of Rare Earth Composite, Henan University of Engineering, Zhengzhou , China |
| WANG Fei-fei |
Henan Key Laboratory of Electronic Ceramic Materials and Application,Henan International Joint Laboratory of Rare Earth Composite, Henan University of Engineering, Zhengzhou , China |
| WANG Yuan |
Henan Key Laboratory of Electronic Ceramic Materials and Application,Henan International Joint Laboratory of Rare Earth Composite, Henan University of Engineering, Zhengzhou , China |
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| Abstract: |
| Polymer-matrix dielectric composites have greatly potential in high power density film energy-storage capacitors due to their advantages such as light weight, high power density, fast charge and discharge rate, wide working voltage, which are widely used in new energy vehicles, smart grids and many other fields. At present, dielectric capacitors show low energy storage density and low discharge efficiency under high working voltage conditions, which hinder the development of energy storage devices and systems towards miniaturization and high capacity. It is of great significance to develop dielectric energy storage materials with higher working field strength and higher energy storage efficiency to improve the performance of power equipment. The composite method can greatly improve the dielectric properties and energy storage properties of polymer materials. However, the introduction of inorganic ceramic fillers leads to the accumulation of space charges at the interface of the composites, resulting in strong interface polarization, as well as high dielectric loss and low discharge efficiency of the composites. The work aims to introduce core-shell structured fillers to reduce the interface polarization. The SrTiO3@Al2O3 nanofiber with a one-dimensional core-shell structure was prepared by electrospinning combined with sol-gel process. The filler was functionalized with 3-aminopropyl triethoxysilane to improve the compatibility between nanofiber filler and PVDF matrix. The PVDF composites were prepared by casting. The effects of Al2O3 coated on the surface of SrTiO3 nanofiber fillers on the interface polarization, dielectric properties and energy storage performance of PVDF dielectric composites were systematically studied. The test results showed that the prepared powder was one-dimensional nanofiller with a good core-shell structure. The core layer was SrTiO3 and the shell layer was Al2O3. The Al2O3 layer was evenly coated on the nanofiber surface with an average coating thickness of 6 nm. At low filling levels, the one-dimensional core-shell nanofiber filler was evenly dispersed in the PVDF. Under the same volume fraction of filler, SrTiO3@Al2O3 nanofiber/PVDF composite exhibited lower dielectric loss and leakage current, as well as higher breakdown strength. At the same time, SrTiO3@Al2O3 nanofiber/PVDF dielectric composites had higher energy storage density than that of SrTiO3 nanofiber/PVDF composites. The energy storage density of SrTiO3@Al2O3 nanofiber/PVDF composite was 8.9 J/cm3. While, the energy storage density of SrTiO3 nanofiber/PVDF composite was 6.8 J/cm3. For the 2.5 vol. % of SrTiO3@Al2O3 nanofiber dielectric composite, it exhibited an efficiency of 84.2% at 1 000 kV/cm and was higher than 64.9% at 3 950 kV/cm. The discharge efficiency of pure PVDF was significantly reduced from 75.4% at 1 000 kV/cm to 42.4% at 4 000 kV/cm. This was because the Al2O3 coating layer prevented the contact of the SrTiO3 nanofiber filler in the composites, which could reduce the interface polarization, significantly reduce the leakage current, and improve the breakdown strength of the composite. This work may supply effective ways to raise discharged energy density of polymer composites in high electric fields. |
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